The present invention relates to a compact fluorescent lamp with a screw base which is to be used in place of an incandescent lamp and, more particularly, to a heat radiation structure which is suitable for the protection of circuit elements in a high frequency electronic ballast (including an oscillator transformer) and a transistor or a FET (Field Effect Transistor), and for improvement of the reliability of the circuit elements.
The high frequency operating circuit section corresponding to such type of compact fluorescent lamp requires a sealed structure and the elements therein need to be highly compacted. In addition, since the operating circuit section is usually located above a lamp, it is subjected to the heat which is generated from the lamp. On the other hand, there are some elements, among the circuit elements contained in the compact fluorescent lamp, which are likely to be adversely influenced by this heat that is being generated. Therefore, the use of a heat radiation fin is considered one type of structure for effectively radiating the heat of the oscillator transformer, which is a heat element or source of heat in the operating circuit section to the atmosphere. Further, another way for improving the heat radiation effect is by enlarging the heat transfer area, as indicated in Japanese Utility Model Examined Publication No. 59-4539, by pouring the insulating compound into the outer case and thereby allowing the ballast (oscillator transformer) to come into contact with this compound, or by a means for enlarging the heat transfer area by molding the transformer using a heat hardened resin. In addition, there has been used the means for attaching the heat radiation fin to the transistor or FET or directly attaching the transistor or FET to the outer case.
According to the above conventional techniques, although the heat radiation effect increases, the total lamp weight also substantially increases due to the pouring of the compound. In the case of molding the transformer with the resin, the productivity decreases and the total cost in turn increases. Also, the pouring of the compound results in the structure becoming complicated, having an increased number of parts, and results in a decrease of productivity. The attachment of the heat radiation fin to the transistor or FET results in an increase in the number of required parts and in a high attachment cost. On the other hand, the method whereby the transistor or FET is directly attached to the outer case results in a very complicated assembled structure. As mentioned above, the conventional technologies have resulted in various problems.